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[flang][driver] deprecate manual usage of -lFortran_main #79016

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Merged
merged 2 commits into from
Jan 22, 2024
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[flang][driver] deprecate manual usage of -lFortran_main #79016

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[flang][driver] deprecate manual usage of -lFortran_main
tblah Jan 22, 2024
1ba503b
Fix review comments
tblah Jan 22, 2024
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2 changes: 2 additions & 0 deletions clang/include/clang/Basic/DiagnosticDriverKinds.td
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Expand Up @@ -427,6 +427,8 @@ def warn_drv_clang_unsupported : Warning<
"the clang compiler does not support '%0'">;
def warn_drv_deprecated_arg : Warning<
"argument '%0' is deprecated, use '%1' instead">, InGroup<Deprecated>;
def warn_drv_deprecated_custom : Warning<
"argument '%0' is deprecated, %1">, InGroup<Deprecated>;
def warn_drv_assuming_mfloat_abi_is : Warning<
"unknown platform, assuming -mfloat-abi=%0">;
def warn_drv_unsupported_float_abi_by_lib : Warning<
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16 changes: 14 additions & 2 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Expand Up @@ -1194,19 +1194,31 @@ static void addFortranMain(const ToolChain &TC, const ArgList &Args,
}

// 2. GNU and similar
const Driver &D = TC.getDriver();
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Move this whole block below the // 2. GNU and similar? Otherwise it seems that this is still part of MSVC processing.

const char *FortranMainLinkFlag = "-lFortran_main";

// Warn if the user added `-lFortran_main` - this library is an implementation
// detail of Flang and should be handled automaticaly by the driver.
for (const char *arg : CmdArgs) {
if (strncmp(arg, FortranMainLinkFlag, strlen(FortranMainLinkFlag)) == 0)
D.Diag(diag::warn_drv_deprecated_custom)
<< FortranMainLinkFlag
<< "see the Flang driver documentation for correct usage";
}

// The --whole-archive option needs to be part of the link line to make
// sure that the main() function from Fortran_main.a is pulled in by the
// linker. However, it shouldn't be used if it's already active.
// TODO: Find an equivalent of `--whole-archive` for Darwin and AIX.
if (!isWholeArchivePresent(Args) && !TC.getTriple().isMacOSX() &&
!TC.getTriple().isOSAIX()) {
CmdArgs.push_back("--whole-archive");
CmdArgs.push_back("-lFortran_main");
CmdArgs.push_back(FortranMainLinkFlag);
CmdArgs.push_back("--no-whole-archive");
return;
}

CmdArgs.push_back("-lFortran_main");
CmdArgs.push_back(FortranMainLinkFlag);
}

/// Add Fortran runtime libs
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4 changes: 4 additions & 0 deletions flang/test/Driver/linker-flags.f90
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Expand Up @@ -11,6 +11,7 @@
! RUN: %flang -### --target=x86_64-unknown-dragonfly %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,UNIX
! RUN: %flang -### --target=x86_64-unknown-haiku %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,HAIKU
! RUN: %flang -### --target=x86_64-windows-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,MINGW
! RUN: %flang -### --target=aarch64-unknown-linux-gnu %S/Inputs/hello.f90 -lFortran_main 2>&1 | FileCheck %s --check-prefixes=DEPRECATED

! NOTE: Clang's driver library, clangDriver, usually adds 'oldnames' on Windows,
! but it is not needed when compiling Fortran code and they might bring in
Expand Down Expand Up @@ -53,3 +54,6 @@
! MSVC-LABEL: link
! MSVC-SAME: /subsystem:console
! MSVC-SAME: "[[object_file]]"

! Check that we warn when using -lFortran_main
! DEPRECATED: warning: argument '-lFortran_main' is deprecated, see the Flang driver documentation for correct usage [-Wdeprecated]